An interesting and well documented experiment by The Typist: a visualization of four years of purchases on the iTunes Store, and particularly the App Store. I can't imagine the amount of effort that went into this (sifting through 90 emails, recalculating prices based on past currency conversions, etc.), but I hope I'll have the patience to do the same someday.
The Typist makes a great point about iOS games:
So what does that mean for games? Of the 34 that I’ve purchased, only 5 games — worth $18 — are currently installed on either of my iOS devices. Of the $111.66 that I’ve spent, $93.71 worth of games are on neither of my devices. Almost 84% of the money I’ve spent on games is now in the cloud.
Does that mean I wouldn’t have bought any or most of them? Not necessarily: That would be like not going to the movies because you pay $12 for 120 minutes that you can’t “reuse”. Most forms of entertainment are ephemeral by nature.
Unlike console games, I can't remember any old iOS game that I intentionally redownloaded to play it again like I do for, say, Nintendo or Squaresoft classics. Maybe it's just me, or maybe it's the nature of mobile games. Also worth considering: old iOS games that don't work properly on current versions of the OS, that don't have Retina assets, or that rely on third-party services no longer in existence (the last one is a problem common to console games, too).